The present invention relates to a magnet valve having a movable member which moves in correspondence to energization of a coil and non-energization thereof and to a fluid control apparatus using the magnet valve. The present invention is favorably applied to an ABS actuator (fluid control apparatus) of an ABS (antilock braking system) for preventing a wheel from having a tendency to locking by increasing or decreasing a brake fluid pressure of a vehicle.
FIG. 10 is a partly sectional view showing the construction of a magnet valve-mounted portion of the ABS actuator described in laid-open Japanese patent publication Toppyo Hei 9-511965.
In the ABS actuator described in this publication, the yoke 43 held together with the spool 41 and the ring 44 as a unit are pressed against the cover 8 by the leaf spring 200, serving as the elastic member, interposed between the yoke 43 and the housing 7. By restraining the movement of the yoke 43 in this manner, a mechanical load generated by loosening of the yoke 43 is prevented from acting on the terminal 42 and the soldering part 11.
A brake control actuator having an antilock function includes various modes. In a mode, eight magnet valves are used and only the antilock function is realized. In a mode, 10 magnet valves are used and the antilock function, a traction control function, and a brake assist function are realized. In a mode, 12 magnet valves are used and the antilock function and an inline traction control function are realized. In a mode, 14 magnet valves are used and the antilock function, an out-line traction control function, and the inline traction control function are realized.
By the way, the inline traction control has a function of pressurizing with a pump a brake fluid sucked from a duct disposed between a master cylinder and a pressure increase control valve and flowing it to a wheel cylinder when the traction control is performed. The outline traction control has a function of pressurizing with the pump the brake fluid sucked from a reservoir of the master cylinder and flowing it to the wheel cylinder when the traction control is performed.
However, in the conventional actuator described in the publication, by interposing one leaf spring 200 between the housing 7 and the yoke 43 of each of a large number of the magnet valves 3, the yokes 43 of all the magnet valves 3 are supported by one leaf spring 200. Thus the conventional actuator has a problem that it is necessary to prepare a plurality of kinds of the leaf springs 200 corresponding to the above-described respective modes and hence a high cost.
It is an object of the present invention to prevent a yoke from loosening without using a plurality of kinds of leaf springs corresponding to respective modes of a fluid control apparatus and reduce the cost.
In the first characteristic of the present invention, there is provided a magnet valve which is used as sandwiched between a first sandwiching member and a second sandwiching member. The magnet valve includes a yoke having a cylindrical part and a flange part extending from one end of the cylindrical part to a radially inward side of the cylindrical part and contacting the first sandwiching member; a spool disposed inside the yoke; a coil wound on the spool and forming a magnetic field when the coil is energized; a movable member moving in correspondence to energization and non-energization of the coil; a magnetic path member disposed at the other end of the cylindrical part and fixed to the second sandwiching member and forming a magnetic path; an elastic member disposed between the magnetic path member and the spool and urging the spool toward the flange part, with one end of the elastic member in contact with the magnetic path member and with the other end thereof in contact with the spool.
In the second characteristic of the present invention, there is provided a fluid control apparatus including a magnet valve; a second sandwiching member having a fluid duct, opened and closed by the magnet valve, formed therein; and a first sandwiching member fixed to the second sandwiching member, with the magnet valve sandwiched between the first sandwiching member and the second sandwiching member.
In the third characteristic of the present invention, there is provided a magnet valve including a yoke having a cylindrical part and a flange part extending from one end of the cylindrical part to a radially inward side of the cylindrical part and forming a magnetic path; a spool disposed inside the yoke; a coil wound on the spool and forming a magnetic field when the coil is energized; a movable member moving in correspondence to energization and non-energization of the coil; a magnetic path member disposed at the other end of the cylindrical part and forming a magnetic path; an elastic member disposed between the magnetic path member and the spool and urging the spool toward the flange part, with one end of the elastic member in contact with the magnetic path member and with the other end thereof in contact with the spool The spool and the yoke are so constructed as to be movable relatively to each other in an axial direction of the yoke, and the yoke and the magnetic path member are so constructed as to be movable relatively to each other in the axial direction of the yoke.
In the fourth characteristic of the present invention, there is provided a fluid control apparatus including a magnet valve in which a yoke accommodates a coil and a spool therein and a movable member moves in correspondence to energization and non-energization of the coil; a second sandwiching member disposed at one end of the magnet valve and having a fluid duct, opened and closed by the movable member, formed therein; and a first sandwiching member disposed at the other end of the magnet valve and fixed to the second sandwiching member, with the magnet valve sandwiched between the first sandwiching member and the second sandwiching member. The first sandwiching member has a projection, a front end of which contacts the yoke and which is deformable when the magnet valve is sandwiched between the first sandwiching member and the second sandwiching member.